2-speed gearbox

Abstract

A two-speed electric drive assembly for a vehicle includes a main drive shaft driven by a first axial flux motor, the main drive shaft axially extending through a hollow assist drive shaft driven by a second axial flux motor. The main drive shaft has a main gear continuously meshed with an intermediate gear provided on the intermediate drive shaft. A freewheel gear is provided about the hollow assist drive shaft, the freewheel gear being selectively connectable and disconnectable from the hollow assist drive shaft by a shift mechanism. The freewheel gear is continuously meshed with an output gear attached to the output drive shaft. The two-speed electric drive assembly is capable of selectively shifting between speed and torque modes without torque interruption.

Description

[Technical field]

[0001] [Citation to Related Applications] This application claims priority to U.S. Provisional Patent Application No. 63 / 285,675, filed December 3, 2021, which is incorporated by reference in its entirety.

[0002] FIELD OF THE DISCLOSURE This disclosure relates generally to a transmission assembly for an electric vehicle, and more particularly to a two-speed gearbox for an axial flux electric motor. [Background technology]

[0003] In popular prior art vehicle drive systems, torque interruptions often occur when shifting from one gear to another because the first gear is disengaged from the drive gear and then the second gear is engaged with the drive gear. This is often manifested by a brief reduction in vehicle speed. Yet another source of torque interruption for electric drive systems comes from the timing of the transmission control unit (TCU), particularly the time it takes to transmit a signal from the TCU to the motor controller and any other electronic components working in conjunction with the electric motor. In such electric drive systems, it is not surprising that the software integrating the various separate electronic and electrical components must typically manage the requirements and validity of these components before performing any action. Such coordination between the separate electronic components increases the calculation and reaction times of the electronic components, which in the case of electric drive systems may also result in a brief reduction in vehicle speed and therefore a torque interruption. Thus, there is a need to reduce torque interruptions to enable quick shifting between gears.

[0004] Furthermore, when such a drive system is driven by an electric motor, it is necessary to use the electric motor to bleed off power from the drive system between disengaging first gear and engaging second gear, turning the electric motor into a generator for a short period of time. In this regard, the amount of energy required to decelerate the rotor of the electric motor is proportional to the mass of the rotor and therefore its inertia. When turning the electric motor into a generator, the entire system must absorb and release or otherwise dampen the energy pulse resulting from the decelerating rotor. This energy pulse, if not properly handled, can damage various electronic components of the system. Thus, there is a need to mitigate this energy pulse during gear shifting. Summary of the Invention

[0005] According to one aspect of the present invention, there is provided an electric drive assembly comprising: A main drive shaft is included, and a main gear is provided along the main drive shaft, a first axial flux motor coupled to the main drive shaft and configured to rotate the main drive shaft; An assist drive shaft is included, and an assist gear is provided along the assist drive shaft, a second axial flux motor coupled to the assist drive shaft and positioned to rotate the assist drive shaft; a first intermediate gear, a second intermediate gear and a third intermediate gear are respectively provided along the intermediate drive shaft, the third intermediate gear being fixed to the intermediate drive shaft; an output drive shaft having an output gear attached to the output drive shaft; The main gear is continuously meshed with the second intermediate gear; The assist gear is continuously meshed with the first intermediate gear, The output gear is continuously meshed with the third intermediate gear; An electric drive assembly is provided, characterized in that one of the main gear, the assist gear, the first intermediate gear or the second intermediate gear is a freewheel gear, the freewheel gear being arranged to be rotatable independently of a drive shaft on which the freewheel gear is fitted.

[0006] According to another aspect of the present invention, there is provided a two-speed electric drive assembly comprising: a first axial flux motor; a main drive shaft having a first end and a second end, the main drive shaft disposed along a first axis and coupled to a first axial flux motor; a second axial flux motor disposed adjacent to the first axial flux motor; an assist drive shaft having a first end and a second end, the assist drive shaft being hollow, the assist drive shaft having an outer drive shaft surface and an inner bore extending therethrough between the first end and the second end of the assist drive shaft, the assist drive shaft being coupled to a second axial flux motor, the main drive shaft extending therethrough so as to be coaxial with the assist drive shaft; A main gear fixed to the main drive shaft, an assist gear attached along the assist drive shaft and rotatable independently of the assist drive shaft; an intermediate drive shaft extending along a second axis, the intermediate drive shaft being parallel to but spaced apart from the first axis; a first intermediate gear attached to the intermediate drive shaft and permanently meshed with the assist gear; a second intermediate gear attached to the intermediate drive shaft and permanently meshed with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft disposed along a first axis but spaced from the first and second drive shafts; an output gear fixed to the output drive shaft and permanently meshed with the third intermediate gear; A two-speed electric drive assembly is provided that includes a shift mechanism mounted along an assist drive shaft and axially movable along the assist drive shaft between a main gear and an assist gear.

[0007] According to yet another aspect of the present invention, there is provided an electric drive assembly comprising: a first axial flux motor; a main drive shaft having a first end and a second end, the main drive shaft disposed along a first axis and coupled to a first axial flux motor; a second axial flux motor; an assist drive shaft having a first end and a second end, the assist drive shaft disposed along a first axis and coupled to the second axial flux motor; A main gear is provided around the main drive shaft. an assist gear provided around an assist drive shaft, one of the main gear or the assist gear being a freewheel gear, the freewheel gear being rotatable independently of the drive shaft on which the freewheel gear is fitted; an intermediate drive shaft extending along a second axis, the second axis being parallel to but spaced apart from the first axis; a first intermediate gear disposed about the intermediate drive shaft and permanently meshed with the assist gear; a second intermediate gear mounted about the intermediate drive shaft and permanently meshed with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft spaced apart from the first and second drive shafts; an output gear fixed to the output drive shaft and permanently meshed with the third intermediate gear; An electric drive assembly is provided which includes a shift mechanism mounted adjacent to a freewheel gear, the shift mechanism being movable axially along a driveshaft from a first position in which the shift mechanism engages the freewheel gear to couple the freewheel gear to the driveshaft, to a second position in which the shift mechanism is disengaged from the freewheel gear.

[0008] Various embodiments of the present invention will become more fully understood from the detailed description provided below and the accompanying drawings of various embodiments of the present invention, in which like reference numbers may indicate identical or functionally similar elements. The embodiments are described in detail below with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0009] [Figure 1a] FIG. 1 is a schematic diagram of one embodiment of a two-speed electric drive assembly, showing where the assist gear is a freewheel gear. [Figure 1b] FIG. 1 is a schematic diagram of one embodiment of a two-speed electric drive assembly where the intermediate gear is a freewheel gear. [Figure 1c] FIG. 1 is a schematic diagram of one embodiment of a two-speed electric drive assembly where the main gear is a freewheel gear. [Figure 1d] FIG. 13 is a schematic diagram of another embodiment of a two-speed electric drive assembly, showing where the intermediate gear is a freewheel gear. [Diagram 2] FIG. 1b is a perspective view of the two-speed electric drive assembly of FIG. [Diagram 3] FIG. 1b is a perspective view of a gearbox of the two-speed electric drive assembly of FIG. [Figure 4] FIG. 1b is a perspective view of one embodiment of a shift mechanism used in the two speed electric drive assembly of FIG. [Diagram 5] FIG. 1b is an exploded perspective view of one embodiment of an axial flux electric motor used in the two-speed electric drive assembly of FIG. [Figure 6] FIG. 6 is a perspective view of a rotor assembly of the axial flux electric motor of FIG. [Figure 7] FIG. 7 is an exploded perspective view of the rotor assembly of FIG. [Figure 8] 8 is an enlarged perspective view of a portion of the rotor core of FIG. 7, showing the layered structure of the rotor core. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Disclosed herein is an electric drive assembly for a vehicle including first and second axial flux motors and four drive shafts: a main drive shaft, a hollow assist drive shaft, an intermediate drive shaft, and an output drive shaft. The main drive shaft is coaxial with and passes through the hollow assist drive shaft. The output drive shaft is spaced apart from the intermediate drive shaft. In some embodiments, the output drive shaft may be collinear with the main drive shaft and the hollow assist drive shaft. Three gears are mounted along the intermediate drive shaft: a first intermediate gear, a second intermediate gear, and a third intermediate gear. A main gear is mounted on the main drive shaft and a first axial flux motor is coupled to the main drive shaft to drive the main gear. An assist gear is mounted along the hollow assist drive shaft and is rotatable relative to the hollow assist drive shaft such that the assist gear can be engaged and disengaged from the hollow assist drive shaft. The second axial flux motor is coupled to and drives the hollow assist drive shaft. Finally, an output gear is attached to the output drive shaft. The assist gear is permanently meshed with the second intermediate gear of the intermediate drive shaft, the main gear is permanently meshed with the second intermediate gear of the intermediate drive shaft, and the output gear is permanently meshed with the third intermediate gear of the intermediate drive shaft. In one or more embodiments, the electric drive assembly further includes a shift mechanism attached adjacent to the hollow assist drive shaft, the shift mechanism operable to shift the assist gear into and out of engagement with the hollow assist drive shaft. In a first power mode, the first axial flux motor can drive the main gear and transmit power to the output gear via the second and third intermediate gears.In the second power mode, the first axial flux motor operates as in the first power mode, but the assist gear is driven by the second axial flux motor while engaged with the hollow assist drive shaft, thereby transferring power to the output gear via each of the first, second and third intermediate gears. In the third power mode, the first axial flux motor is allowed to freewheel and only the second axial flux motor is utilized to transfer power to the output gear via the first and third intermediate gears.

[0011] Referring to FIG. 1a, an electric drive assembly 100 is provided that employs two axial flux motors 102a, 102b and gearing to reduce torque interruption. The first axial flux motor 102a is coupled to and drives a main or first drive shaft 104a that extends along a first axis 110. A main gear 114 is disposed along the main drive shaft 104a. The main gear 114 may be integrally formed with the main drive shaft 104a, or alternatively, the main gear 114 may be attached to the main drive shaft 104a for rotation therewith. In one or more embodiments, the main gear 114 is fixed to the main drive shaft 104a. In any case, the main drive shaft 104a has a first end 106a and a second end 106b. In one or more embodiments, the main gear 114 is mounted at the second end 106b of the main drive shaft 104a, and the first axial flux motor 102a is engaged to the first end 106a of the main drive shaft 104a. As used herein, the term axial flux motor refers to an electric device having at least one rotor and corresponding stator spaced axially along the drive shaft axis. Such motors typically incorporate magnets arranged in a plane parallel to the coils. Additionally, as used herein, the term two-speed refers to a gearbox or transmission having two different gear ratios.

[0012] The second flux motor 102b drives the assist or second drive shaft 104b. In one or more embodiments, the second axial flux motor 102b is located adjacent to the first axial flux motor 102a. In either case, the assist drive shaft 104b has a first end 108a and a second end 108b, with an inner bore 113 passing between the first end 108a and the second end 108b, such that the assist drive shaft 104b is hollow along the length of the assist drive shaft 104b. The assist drive shaft 104b also has an outer drive shaft surface 112. An assist gear 116 is provided along the surface 112 of the drive shaft 104b of the assist drive shaft 104b. The assist drive shaft 104b is coupled to the second axial flux motor 102b at the first end 104a of the assist drive shaft 104b. The main drive shaft 104a axially extends through the assist drive shaft 104b so as to be coaxial with the assist drive shaft 104b along a first axis 110. In one or more embodiments, the assist gear 116 is disposed along the assist drive shaft 104b adjacent the outer drive shaft surface 112 and is rotatable relative to the assist drive shaft 104b. Thus, the assist gear 116 can freewheel relative to the assist drive shaft 104b when not coupled to the assist drive shaft 104b. In other words, the assist gear 116 is disposed along the assist drive shaft 104b but can rotate independently of the assist drive shaft 104b when not coupled to the assist drive shaft 104b by a shift mechanism 132, described below.

[0013] In one embodiment, the assist gear 116 may be supported on the outer drive shaft surface 112 of the assist drive shaft 104b by bearings 121 that allow the assist gear 116 to freewheel, i.e., rotate independently of the assist drive shaft 104b. Similarly, a bearing 121 may be mounted within the inner bore 113 of the assist drive shaft 104b to support the main drive shaft 104a, thereby allowing the main drive shaft 104a to rotate independently of the assist drive shaft 104b.

[0014] Because the main drive shaft 104a and the assist drive shaft 104b are coaxial, and the assist drive shaft 104b is a hollow drive shaft with a through bore for the main drive shaft 104a to pass through, the first and second axial flux motors 102a, 102b, respectively, may be positioned adjacent to each other, while the two drive shafts 104a, 104b, respectively, can rotate independently of each other.

[0015] An intermediate or third drive shaft 118 is spaced apart from the main drive shaft 104a and the assist drive shaft 104b, and the intermediate drive shaft 118 extends along a second axis 120. In one or more embodiments, the second axis 120 is parallel to but spaced apart from the first axis 110 such that the intermediate drive shaft 118 is parallel to the main drive shaft 104a and the assist drive shaft 104b. The intermediate drive shaft 118 has a first end 119a and a second end 119b.

[0016] A first intermediate gear 122, a second intermediate gear 124, and a third intermediate gear 126 are disposed along the intermediate drive shaft 118. As shown, in one or more embodiments, the first intermediate gear 122 is mounted adjacent the first end 119a of the intermediate drive shaft 118, the third intermediate gear 126 is mounted adjacent the second end 119b of the intermediate drive shaft 118, and the second intermediate gear 124 is mounted on the intermediate drive shaft 118 between the first intermediate gear 122 and the third gear 126. In other embodiments, the first intermediate gear 122, the second intermediate gear 124, and the third intermediate gear 126 may be mounted on the intermediate drive shaft 118 in a different order. For example, in one or more embodiments, the third intermediate gear 126 may be disposed between the first intermediate gear 122 and the second intermediate gear 124, with an output drive shaft 128 spaced apart from each of the first axis 110 and the second axis 120 for the purpose of housing an output gear 130 permanently meshed with the third intermediate gear 126.

[0017] 1a, the first intermediate gear 122 is permanently meshed with the assist gear 116 such that the first intermediate gear 122 and the assist gear 116 are in contacting engagement with each other. Similarly, the second intermediate gear 124 is permanently meshed with the main gear 114 such that the second intermediate gear 124 and the main gear 114 are in contacting engagement with each other.

[0018] The electric drive assembly 100 further includes an output or fourth output shaft 128. As shown in FIG. 1a, the output drive shaft 128 is radially spaced from the intermediate drive shaft 118. In one or more embodiments, the output drive shaft 128 may extend along the first axis 110 so as to be collinear with the main drive shaft 104a and the assist drive shaft 104b, in which case the output drive shaft 128 is axially spaced from the main drive shaft 104a and the assist drive shaft 104b. In other embodiments, the output drive shaft 128 may extend along a third axis (not shown) separate from the first axis 110 and the second axis 120. In any event, the output drive shaft 128 has a first end 129a and a second end 129b, and an output gear 130 is attached to the output drive shaft 128 between the two ends 129a, 129b and coupled to a third intermediate gear 126 carried by the intermediate drive shaft 118. Specifically, the output gear 130 is permanently meshed with the third intermediate gear 126 such that the third intermediate gear 126 and the output gear 130 are in contacting engagement with one another. In one embodiment, the output gear 130 is attached to the output drive shaft 128 adjacent the first end 129a and a drive flange 135 is attached to the output drive shaft 128 adjacent the second end 129b.

[0019] As used herein, the term "permanently meshed" means that two gears are in contacting engagement or continuously meshed with each other during operation of the electric drive assembly 100. In this regard, all intermediate gears described herein, i.e., first intermediate gear 122, second intermediate gear 124, and third intermediate gear 126, are simultaneously permanently meshed with their respective gears during operation of the electric drive assembly 100. It is notable that since the various gears are in contacting engagement as described herein, the axial and radial spacing between the various drive shafts, i.e., first drive shaft 104a, second drive shaft 104b, third drive shaft 118, and fourth drive shaft 128, may be constant. In other words, all of the drive shafts may be axially and radially fixed relative to each other, thereby minimizing the size of the gearbox housing 133 provided to enclose the gears and drive shafts. 1a specifically illustrates the first and second drive shafts 104a, 104b passing through the gearbox house 133, with the first and second axial flux motors 102a, 102b located external to the gearbox housing 133. Similarly, the fourth drive shaft 128 passes through the gearbox housing 133, with the drive flange 135 also located external to the gearbox housing 133.

[0020] In the illustrated embodiment, the main gear 114 has a first radius R1, the assist gear 116 has a second radius R2, the first intermediate gear 122 has a third radius R3, the second intermediate gear 124 has a fourth radius R4, the third intermediate gear 126 has a fifth radius R5, and the output gear 130 has a sixth radius R6. Of course, the various radii of the gears may be selected to achieve a particular gear ratio, and the present disclosure is not limited to a particular gear ratio. However, in some embodiments, R3 is greater than R4, R4 is greater than R5, R6 is greater than R1, and R1 is greater than R2.

[0021] 1a, gears 114, 116, 122, 124, 126, 130 are generally shown as spur gears, but may be other types of gears, such as, but not limited to, helical gears. In one or more embodiments, output gear 130, main gear 114, and first intermediate gear 122 are bull gears that are larger in diameter than the gears with which they are successively meshed.

[0022] Of course, the particular physical arrangement of the gears and shafts relative to one another is not limited by this disclosure, so long as the various gears are permanently meshed to transmit power as described herein. For example, the output drive shaft 128 may be disposed along an axis different from the first axis 110. Additionally, the output drive shaft 128 may be located adjacent to the axial flux motor 102, in which case the third intermediate gear 126 may be disposed at a first end 119a of the intermediate drive shaft 118, with the second intermediate gear 124 disposed at a second end 119b of the intermediate drive shaft 118. Similarly, while the illustrated gears are shown as spur gears and the various drive shafts are parallel to one another, in other embodiments the gears may be other types of gears such that the drive shafts may be angled relative to one another. For example, the third intermediate gear 126 may be a bevel gear such that the output drive shaft 128 is perpendicular to the intermediate drive shaft 118. Finally, unlike the prior art, with these fixed components, there are no gears or drive shafts that are "shifted" in the sense of being physically moved to change gears. Instead, electric drive assembly 100 exhibits torque and power mode gear transitions utilizing the gear arrangement relationships described above.

[0023] The electric drive assembly 100 further includes a shift mechanism 132 configured to at least couple and decouple the assist gear 116 to the assist drive shaft 104. While not limited to a particular mechanism or device, in one or more embodiments, the shift mechanism 132 may include a cooperating element 137 that engages a cooperating element on the assist gear 116. In some embodiments, the shift mechanism 132 may include an axially slidable dog link or shift sleeve 132b (see FIG. 4). In one or more embodiments, the shift mechanism 132 is located adjacent to the assist gear 116. In this regard, the shift mechanism 132 may be disposed along the first axis 110 and between the main gear 114 and the assist gear 116 for the purpose of at least coupling the assist gear 116 to the assist drive shaft 104b as needed. For example, the shift mechanism 132 may be attached to and coupled to the assist drive shaft 104b such that rotation of the assist drive shaft 104b rotates the shift mechanism 132. In either case, the shift mechanism 132 may be adapted to engage and disengage the assist gear 116 to couple and decouple the assist gear 116 and the assist drive shaft 104b, respectively. In other embodiments, the shift mechanism 132 may be adapted to alternately engage either the assist gear 116 or the main gear 114. If the shift mechanism 132 is adapted to engage either the assist gear 116 or the main gear 114, the shift mechanism 132 may be moved to work with the main gear 114 to increase speed or to work with the assist gear 116 to increase torque from the electric drive assembly 100.

[0024] 1a, an actuator 142 may be utilized to move the shift mechanism 132 into and out of engagement with the gears as desired. In some embodiments, the shift mechanism 132 may include a linkage 140 that urges the shift mechanism 132 between an engaged position and a disengaged position. In one or more embodiments, the actuator 142 is an electrical actuator mechanism.

[0025] Utilizing the shift mechanism 132 allows the second axial flux motor 102b to be utilized in conjunction with the first axial flux motor 102a without resulting in torque interruption, or vice versa. In one illustrative example, the first axial flux motor 102a drives the main gear 114, which in turn rotates the second intermediate drive shaft 118 through the second intermediate gear 124 that is continuously meshed with the main gear 114. The rotating second intermediate drive shaft 118 drives the first intermediate gear 122 that is continuously meshed with the assist gear 116 mounted about the assist drive shaft 104b. In particular, the assist gear 116 is mounted about the assist drive shaft 104b to spin freely or independently of the assist drive shaft 104b when not coupled to the assist drive shaft 104b by the shift mechanism 132. For example, the first axial flux motor 102a can be operated at a selected first speed RPM1 such that the assist gear 116 rotates at an assist gear speed RMP a The second axial flux motor 102b does not need to be operational when the first axial flux motor 102a is operational. To enable the second flux motor 102b to be utilized in conjunction with the first axial flux motor 102a, the second axial flux motor 102b is utilized to rotate the assist drive shaft 104b, which in turn rotates the shift mechanism 132 that is attached to the assist drive shaft 104b. The second motor 102b rotates the shift mechanism 132 at an assist gear speed RMP aIn other words, the first and second axial flux motors 102a, 102b are operated at a second speed RPM2 selected to rotate at the same speed as the rotational speed RMP of the shift mechanism 132. a The first axial flux motor 102a, 102b may be operated at a speed that can be synchronized with but otherwise coincide with the assist gear 116, at which point the shift mechanism 132 may be operated such that the shift mechanism 132 engages the assist gear 116, thereby coupling the assist gear 116 to the assist drive shaft 104b. The second axial flux motor 102b may then be utilized to provide additional torque to the output drive shaft 128, or alternatively, the first and second axial flux motors 102a, 102b may be adjusted to achieve a desired torque-output for the electric drive assembly 100. With this configuration, the second axial flux motor 102b may be operated to help drive the output drive shaft 128 without causing any torque interruption, and in particular without having to disengage any of the gears. Thus, power may be maintained during the entire process.

[0026] To aid in matching the speeds as described above, one or more speed sensors 146 may be provided adjacent at least one of the drive shaft gears to monitor the rotational speed of the drive shaft and / or gears. In the illustrated embodiment, speed sensor 146a is illustrated adjacent the assist drive shaft 104b, speed sensor 146b is illustrated adjacent the intermediate drive shaft 118, speed sensor 146c is illustrated adjacent the output drive shaft 128, and speed sensor 146d is illustrated adjacent the main drive shaft 104a. Those skilled in the art will appreciate that such speed sensors 146 may be positioned to measure the rotational speed of the drive shaft or the rotational speed of the gears attached to the drive shaft. Additionally, while four speed sensors 146 are illustrated for some embodiments, in other embodiments, only two sensors 146 need be utilized to measure the relative RPM resulting from the first and second flux motors 102a, 102b. Alternatively, where there is no need for a speed sensor 146, the speed of the second axial flux motor 102b may be adjusted based on the known speed of the first axial flux motor 102a and the known geometries of the various drive shafts and gears.

[0027] In one or more other embodiments, such as that shown in FIG. 1b, the relative positions of the two meshed gears may be reversed without utilizing the assist gear 116 on the assist drive shaft 104b as a "freewheel" gear and without continuously engaging the fixed first intermediate gear 122 mounted on the intermediate drive shaft 118. Specifically, the assist gear 116 may be a fixed gear mounted on the assist drive shaft 104b, and the first intermediate gear 122 may be a freewheel gear mounted about the intermediate drive shaft 118. In such a case, the first intermediate gear 122 rotates about the second axis 120 independently of the intermediate drive shaft 118. Of course, in this embodiment, a shift mechanism 132 is disposed adjacent to the first intermediate gear 122 for coupling and decoupling the first intermediate gear 122 to and from the intermediate drive shaft 118. In this regard, the shift mechanism 132 may move axially along the second axis 120. A bearing 121 may be utilized between the first intermediate gear 122 and the intermediate drive shaft 118 to enable independent rotation of the first intermediate gear 122 relative to the intermediate drive shaft 118.

[0028] In one or more other embodiments, as shown in FIG. 1c, rather than utilizing an assist gear 116 attached to the assist drive shaft 104b as a "freewheel" gear, the assist gear 116 may be a fixed gear attached to the assist drive shaft 104b, and the main gear 114 mounted about the main drive shaft 104a may be utilized as a freewheel gear. In such a case, the main gear 114 rotates about the first axis 110 independently of the main drive shaft 104a. As will be appreciated, in this embodiment, a shift mechanism 132 is disposed adjacent to the main gear 114 for engaging and disengaging the main gear 114 from the main drive shaft 104a. A bearing 121 may be utilized between the main gear 114 and the main drive shaft 104a, thereby allowing independent rotation of the main gear 114 relative to the main drive shaft 104a.

[0029] In one or more other embodiments, as shown in FIG. 1d, instead of utilizing the main gear 114 on the main drive shaft 104a as a "freewheel" gear that is continuously meshed with the fixed gear 124 attached to the intermediate drive shaft 118, the relative positions between these two meshed gears may be reversed. Specifically, the main gear 114 may be a fixed gear attached to the main drive shaft 104a, and the first intermediate gear 124 may be a freewheel gear attached about the intermediate drive shaft 118. In such a case, the second intermediate gear 124 rotates about the second axis 120 independently of the intermediate drive shaft 118. As will be appreciated, in this embodiment, a shift mechanism 132 is disposed adjacent to the second intermediate gear 124 for engaging and disengaging the second intermediate gear 124 from the intermediate drive shaft 118. In this regard, the shift mechanism 132 may move axially along the second axis 120. A bearing 121 may be utilized between the second intermediate gear 124 and the intermediate drive shaft 118 , allowing independent rotation of the second intermediate gear 124 relative to the intermediate drive shaft 118 .

[0030] Thus, based on the above, various embodiments generally include four optional positions for the freewheel gear and two optional positions for the shift mechanism 132. In this regard, the electric drive assembly 100 can be said to include a main drive shaft 104a, an assist drive shaft 104b, an intermediate drive shaft 118, and an output drive shaft 128. The main gear 114 is disposed along the main drive shaft 104a, the assist gear 116 is disposed along the assist drive shaft 104b, the first, second and third intermediate gears 122, 124, 126 are disposed along and spaced apart from one another along the intermediate drive shaft 118, respectively, and the output gear 130 is attached to the output drive shaft 128. The main gear 114 is continuously meshed with the second intermediate gear 124, the assist gear 116 is continuously meshed with the first intermediate gear, and the output gear 130 is continuously meshed with a third intermediate gear 126, which is fixed to the intermediate drive 118. One of the main gear 114, the assist gear 116, the first intermediate gear 122 or the second intermediate gear 124 is a freewheel gear mounted to be rotatable independently of the drive shaft to which it is fitted. A shift mechanism is mounted adjacent to the freewheel gear and is axially movable to couple and uncouple the freewheel gear to the drive shaft to which it is fitted.

[0031] Referring to FIG. 2, another embodiment of the electric drive assembly 100 is shown. In the illustrated embodiment, an assist gear 116 is disposed about the assist drive shaft 104b. The assist gear 116 is axially constrained along the assist drive shaft 104b, but is not attached to the assist drive shaft 104b, and is instead disposed to rotate independently of the assist drive shaft 104b. The assist drive shaft 104b may be supported by a bearing 121 mounted on a first side 115 of the gearbox housing 133 and a first support plate 131 disposed within the gearbox housing 133 and spaced from the first side 115. The assist drive shaft 104b passes through the gearbox housing 133 and is driven by a second axial flux motor 102b. The shift mechanism 132 is shown positioned adjacent to the assist gear 116 to allow selective engagement of the shift mechanism 132 with the assist gear 116 when the shift mechanism 132 is actuated.

[0032] The main drive shaft 104a is shown passing through the second axial flux motor 102b and the assist drive shaft 104b. The first axial flux motor 102a drives the main drive shaft 104a. A main gear 114 is attached to (or formed integrally with) the main drive shaft 104a such that rotation of the main drive shaft 104a by the first axial flux motor 102a drives the main gear 114. In the illustrated embodiment, the main drive shaft 104a passes completely through and protrudes from the assist drive shaft 104b such that the main drive shaft 104a can be supported by bearings 121 provided in the gearbox housing 133 and supported on a second support plate 131b disposed between the first support plate 131a and the second side 117 of the gearbox housing 133. Although the main gear 114 is shown attached to the main drive shaft 104a such that the main gear 114 is positioned between the second support plate 131b and the second side 117, the main gear 114 can be attached to the main drive shaft 104a on the opposite side of the second support plate 131b such that the main gear 114 is positioned between the first support plate 131a and the second support plate 131b.

[0033] In the illustrated embodiment, the second intermediate gear 124 is supported by an intermediate drive shaft 118 and is in continuous mesh with the main gear 114. The intermediate drive shaft 118 is supported by the gearbox housing 133 and the first side 115, the second side 117 of the gearbox housing 133 and in some embodiments may be mounted in a bearing 121 supported by one or both support plates 131 a, 131 b, or by any of these means.

[0034] A first intermediate gear 122 is also attached to the intermediate drive shaft 118 and is in continuous mesh with the assist gear 116 disposed about the assist drive shaft 104b.

[0035] Finally, an output drive shaft 128 is shown supported between the second side 117 of the gearbox housing 133 and the second support plate 131b. The output drive shaft 128 may also be supported by bearings 121 on the second support plate 131b, but it should be noted that the output drive shaft 128 is separate and spaced from the main drive shaft 104a. In any event, an output gear 130 is attached to the output drive shaft 128 and is in continuous mesh with a third intermediate gear 126 supported on the intermediate drive shaft 118.

[0036] A shift mechanism 132 is shown mounted adjacent the assist gear 116. The shift mechanism 132 may be operable to selectively engage and disengage the assist gear 116 from the assist drive shaft 104b. When the assist gear 116 is engaged with the assist drive shaft 104b by the shift mechanism 132, power from the second axial flux motor 102b may be transferred to the intermediate drive shaft 118 to assist the power from the first axial flux motor 102a being transferred to the intermediate drive shaft 118 by the main gear 114. It will be appreciated that in one or more embodiments where R3>R4>R5 and R6>R1>R2, the power from the second axial flux motor 102b may be utilized to increase the output torque by the output drive shaft 128. Additionally, when the speed of the output drive shaft 130 is desirable compared to the torque, the shift mechanism 132 can be actuated to disengage the assist gear 116 from the assist drive shaft 104b so that only the first axial flux motor 102a drives the output drive shaft 128.

[0037] One or more speed sensors 146 can be used to measure the timing of the drive shafts and / or gears so that the RPM of one or both axial flux motors can be adjusted to facilitate engagement of the assist gear 116 and the assist drive shaft 104b by the shift mechanism 132. Although Figure 2 shows speed sensors 146b, 146c, and 146d, this disclosure is not limited to any particular number or placement of speed sensors 146 unless otherwise specified.

[0038] 3 is similar to FIG. 2, but omits the axial flux motors 102a, 102b and the gearbox housing 133 to better illustrate additional components of embodiments of the electric drive assembly 100. For example, although not required, in some embodiments the shift mechanism 132 may be driven by an actuator 142 (also shown in FIG. 1a). In some embodiments, the actuator 142 may be an electric actuator for urging the shift mechanism 132 between a number of positions to couple the freewheel gear to a drive shaft, e.g., the assist drive shaft 104b, including at least a first "neutral" position in which the shift mechanism 132 is not engaged with a gear and a second position in which the shift mechanism 132 is engaged with the freewheel gear, e.g., the assist gear 116. Some embodiments may include a third position in which the shift mechanism 140 engages the main gear 114 to couple the main gear 114 to the assist drive shaft 104b in another configuration to utilize both the first axial flux motor 102a and the second axial flux motor 102b as a power source for the output drive shaft 128.

[0039] In FIG. 3, a speed sensor 146b is provided adjacent to the intermediate drive shaft 118 to monitor the rotation of the intermediate drive shaft 118, and a speed sensor 146c is disposed adjacent to the output drive shaft 128 to monitor the rotation of the output drive shaft 128.

[0040] In the embodiment shown in Figures 2 and 3, gears 114, 116, 122, 124, 126, and 130 are shown as helical gears, however, in other embodiments, various types of gears may be utilized.

[0041] Referring back to FIG. 1a and with reference to FIG. 4, one embodiment of the shift mechanism 132 is shown in FIG. 4, although the shift mechanism 132 is not limited to any particular configuration. In this embodiment, the shift mechanism 132 utilizes cooperating elements, such as cooperating elements 136a and 137, shown in FIG. 4, to engage with one another. In particular, the shift mechanism 132 includes a stationary hub 134 mounted to the assist drive shaft 104b (see FIG. 1a) for rotation therewith. The illustrated shift mechanism 132 further includes a dog ring or shift sleeve 136 that slidably engages the stationary hub 134. The shift sleeve 136 is axially movable relative to the stationary hub 134. In one or more embodiments, the shift sleeve 136 has one or more cooperating elements 136a that engage with one or more cooperating elements 134a of the stationary hub 134 to constrain the shift sleeve 136 to axial movement along the first axis 110. In some embodiments, the cooperating elements may be teeth. In the illustrated embodiment, the cooperating elements 134a are formed around the outer periphery of the stationary hub 134 and the cooperating elements 136a are formed around the inner periphery of the shift sleeve 136.

[0042] Additionally, the cooperating element 136a of the shift sleeve 126 may function as an engagement mechanism that allows the shift sleeve 136 to couple with an adjacent gear, such as the assist gear 116 described in FIG. 1a and shown in FIG. 4. To facilitate such coupling, the adjacent gear may further include one or more cooperating elements 137 that may engage with the cooperating element 136a of the shift sleeve 136. In such a case, the cooperating element 136a may engage with both the cooperating element 134a of the fixed hub 134 and the cooperating element 137 of the assist gear 116. In some embodiments, the cooperating element 136a may allow the shift sleeve 136 to couple with the main gear 114 upon disengagement from the assist gear 116. In such a case, the main gear 114 may similarly be formed with the cooperating element 137. Similarly, instead of utilizing a cooperating element 136a formed around the inner circumference of the shift sleeve 136, a cooperating element 137 may be formed on one or both end faces 136b of the shift sleeve 136 such that it is engageable with a cooperating element 137 of the gear.

[0043] In other embodiments, the shift sleeve 136 may have one or more first cooperating elements 136a adapted to engage and disengage with the assist gear 116 and one or more second cooperating elements 136a adapted to engage and disengage with the main gear 114. In such a case, a cooperating element 136a may be provided on each of the opposing end faces 136 of the shift sleeve 136. In any event, the cooperating elements described herein may have extensions, teeth, knobs, recesses, protrusions, and the like, so long as the cooperating elements engage with one another. For example, teeth may engage teeth, or protrusions may engage recesses. In one or more embodiments, the cooperating elements 137 provided on the gears may be provided around the periphery or face of the gears, such as shown on the end face 116a of the assist gear 116 in FIG. 4. In the illustrated embodiment, the cooperating elements 137 extend axially away from the end face 116a of the assist gear 116 toward the shift mechanism 132. Instead of or in addition to cooperating elements provided about the inner circumference of the shift sleeve 136 for engaging adjacent gears, cooperating elements 136a may be formed on each or both of the opposing end faces 136b of the shift sleeve 136.

[0044] In particular, in the above-described configuration of the electric drive assembly 100, the first and second axial flux motors 102a, 102b may be utilized to synchronize the rotational speed of the assist gear 116 with the assist drive shaft 104b, thereby eliminating the need for traditional synchronizer or blocker rings of the prior art, as well as the need for friction cones on the gears as commonly utilized in the prior art for coupling. In the electric drive assembly 100, once the rotational speed of the freewheel gear, e.g., the assist gear 116, and the drive shaft to which it is fitted, e.g., the assist drive shaft 104b, are synchronized under the control of the axial flux motors 102a, 102b, the shift sleeve 136 may be engaged with the assist gear 116 by the cooperating elements 136a and 137, respectively. Additionally, in some embodiments, the main gear 114 may further include one or more cooperating elements 137 formed thereon for engagement with cooperating elements 136a of the shift sleeve 136 upon disengagement from the assist gear 116, thereby allowing the second axial flux motor 102b to assist in driving the main gear 114. The above configuration eliminates the need for friction cones, which are common in the prior art. Of course, by eliminating the need for traditional synchronizer rings and friction cones, the axial length and relative weight of the electric drive assembly 100 may also be reduced.

[0045] In one or more embodiments, the shift mechanism 132 can move axially along the assist drive shaft 104b to direct the output from the second axial flux motor 102b to the output drive shaft 128 via the main gear 114 and the assist gear 116. In some embodiments, a linkage 140, e.g., a shift fork, can be utilized by the shift mechanism 132 to move between a first position in which the shift mechanism 132 is engaged with one gear, a second position in which the shift mechanism 132 is disengaged from any gear, and a third position in which the shift mechanism 132 is engaged with another gear. In such embodiments, at least one of the gears is a freewheel gear as described and generally illustrated by the assist gear 116 in FIG. 1a.

[0046] To optimize engagement of cooperating element 136a of shift mechanism 132 with cooperating element 137 of assist gear 116, one or more speed sensors 146 may be provided adjacent at least one of the drive shaft or gears to monitor the rotational speed of the drive shaft and / or gears. Because the position of the speed sensor 146 relative to the engagement mechanism may be fixed, the shift mechanism may be shifted into full engagement without utilizing a synchronizer system of the prior art.

[0047] 1a, in one or more embodiments, a single inverter 144 may be electrically coupled to each of the first and second axial flux motors 102a, 102b and the electric actuator 142 to reduce latency. In such a case, the speed sensor 146 may operate in coordination with a single controller 148 that controls each of the first and second axial flux motors 102a, 102b and the electric actuator 142. Because a single inverter 144 may be utilized for both axial flux motors 102a, 102b, the need for separate electrical components that would otherwise be common in the prior art, such as a telematic control unit ("TCU") that must communicate with multiple inverters, may be eliminated, thereby reducing latency in the operation of the electric drive assembly 100.

[0048] As will be appreciated, the gear ratios are flexible and can be selected for each of the gears to achieve the desired results. In any event, since the main gear 114 is constantly engaged and driven by the first axial flux motor 102a, there is no drop off or torque interruption when the shift mechanism 132 is shifted to utilize the output from the second axial flux motor 102b, whether by the main gear 104 or the assist gear 116. It is the two separate axial flux motors 102a, 102b working together with the constantly engaged gearing mechanism described that allows for the torque interruption to be mitigated as described. In any event, since the main gear 114 is constantly engaged and driven when the first axial flux motor 102a is operating, there is no drop off in the speed of the main gear 114 when the shift mechanism 132 is shifted to engage or disengage the assist gear 116.

[0049] In one or more embodiments, a speed sensor 146b is provided adjacent the intermediate drive shaft 118 to monitor the rotation of the intermediate drive shaft 118. As will be appreciated, the shift mechanism 132, and in particular the shift sleeve 136, may include one or more engagement mechanisms or cooperating elements, such as teeth, extensions, knobs, recesses, protrusions, etc., provided to couple with the assist gear 116 and, in some embodiments, with cooperating elements also provided on the main gear 114. By knowing the rotational speed of the intermediate drive shaft 118, the gears 116, 114 may be fully engaged without torque interruption or the need for any intermediate friction couplings utilizing friction cones. This synchronization comes from one or more of the speed sensors 146. Once the entire electric drive assembly 100 is assembled, the relative relationships or positions of the main gear, assist gear, intermediate gear, and output gear are fixed and do not change over time. Therefore, by knowing the rotational speed of the intermediate drive shaft (or another component of the main, intermediate or output system), the speed of the second axial flux motor 102b can be adjusted accordingly to synchronize engagement of the shift mechanism 132 with either the main gear 114 or the assist gear 116.

[0050] Referring to another novel aspect of the electric drive assembly 100 described above, since there are two axial flux motors 102a, 102b, one of the axial flux motors 102 can be utilized to generate power when the electric drive assembly 100 is switched from speed mode to torque mode. In particular, it will be appreciated that at times, a particular gear ratio utilizing only the assist gear 116 may be desirable. In such a case, since the main gear 114 is constantly engaged with the second intermediate gear 124 and the main drive shaft 104a is constantly in motion, the first axial flux motor 102a driven by the main drive shaft 104a can be utilized in a regenerative mode to generate power as an alternator, much like using the rotational speed / torque bled off through either drive shaft 104 to drive the axial flux motor 102, thereby generating power. In one or more embodiments where electricity is produced from one of the axial flux motors 102a, 102b, an inverter 144 may also be utilized to manage power generation. Of course, the larger the electrical pulse resulting from regeneration (which may occur during a transition from a high speed mode utilizing the first axial flux motor 102a to a high torque mode utilizing the second axial flux motor 102b), the longer the period required to decay or bleed off the electricity produced from the flux motor 102a. Furthermore, the larger the pulse, the greater the amount of heat that can be managed by the inverter 144, which may be necessary to prevent heating of various electrical components. Thus, it is desirable to minimize the regeneration mode of the axial flux motor during gear transitions between the torque and power modes of the electric drive assembly 100.

[0051] 5, to minimize the amount of regeneration from the axial flux motor 102 during gear transitions between torque and power modes, in one or more embodiments, one or both axial flux motors 102 include rotor assemblies that include non-magnetic components constructed primarily of non-conductive materials, such as composites or polymers, to reduce the weight of the rotor assemblies. Such a configuration minimizes energy pulse damping in the motor prior to synchronization as discussed above. Thus, for example, referring to FIG. 5, an axial flux electric motor assembly is shown. The electric motor assembly 200 includes at least one rotor assembly 210 and at least one stator assembly 212 axially spaced apart from one another along a motor axis 214. In the illustrated embodiment, a rotor spindle or drive shaft 216 extends along the axis 214 and supports the rotor assembly 210. The rotor drive shaft 216 may have a spindle flange 217 attached to the rotor assembly 210. The rotor drive shaft 216 may be supported by one or more bearings 218 .

[0052] While only one stator assembly 212 may be utilized, in the illustrated embodiment, two stator assemblies 212a, 212b are shown disposed on opposite sides of the single stator assembly 210 along the axis 214. It will be appreciated that by minimizing the number of rotor assemblies, the overall weight of the axial flux motor 200 used in the electric drive assembly 100 may be minimized, in particular to minimize the need for energy pulse damping when alternating between speed and torque modes as described above. In this regard, the gearing of the electric drive assembly 100 described herein is well suited to a pair of single axial flux motors as described in some embodiments, since each of the axial flux motors may be utilized as needed to achieve the desired output without limiting potential energy pulses that may result from rotors with larger mass and inertia.

[0053] Motor housing 220 and opposing stator supports or end plates 222 enclose rotor assembly 210 and one or more stator assemblies 212. In one or more embodiments, at least one end plate 222 supports a stator assembly 212 on an inner surface 223 of end plate 222. In the illustrated embodiment, end plate 222a supports stator assembly 212a and end plate 222b supports stator assembly 212b.

[0054] Where the end plate 222 supports the stator assembly 212 , the end plate 222 may include a cooling mechanism 224 disposed along an outer surface 226 of the end plate 222 .

[0055] In one or more embodiments, the cooling mechanism 224 may form one or more coolant passages 228 along the outer surface 226 of the end plate 222. The coolant passages 228 may be one or more cooling channels 230 formed in the outer surface 226 of the end plate 222.

[0056] In the illustrated embodiment, a plurality of fluidly coupled cooling channels 230 are shown generally arranged to extend around the end plate 222 opposite the stator assembly 212 located on the inner surface 223 of the end plate 222. While not limited to a particular configuration, in one embodiment, the coolant 230 may form a star shape along the outer surface 226 to maximize cooling while allowing the various motor components to be secured to the end plate 222 from the inner surface 223 without the fasteners 227 extending through the end plate 222 to the outer surface 226 of the end plate 222. In other words, threaded bores may be formed on the inner surface 223 of the end plate 222 that can mate with the fasteners 227, but the bores do not extend completely through the end plate 222. It will be appreciated that such a configuration minimizes the risk of fluid within the rotor assembly 200 leaking or escaping, or vice versa. In other embodiments, the coolant passages 228 may be formed with tubes (not shown) disposed on the exterior surface 226. In yet another embodiment, the coolant passages 228 may be formed with ribs or fins (not shown) extending from the exterior surface 228, while in other embodiments, the coolant passages 228 may simply be coolant chambers formed between the end plate 222 and the outer plate 234. Notwithstanding the above configuration, it will be appreciated that the cooling channels 230 formed in the exterior surface 226 of the end plate 222 may be particularly desirable in minimizing the overall axial length of the electric drive assembly 200. In any event, one or more ports 225 in fluid communication with the passages 228 may be utilized to introduce or withdraw coolant from the cooling mechanism 224.

[0057] Each stator assembly 212 is generally formed of a stator core 234 and stator windings 240, as known to those skilled in the art. In this regard, the stator windings 240 may be formed from electrical wire. The present disclosure is not limited to any particular configuration for the stator assembly 212.

[0058] 6 and 7, with continued reference to FIG. 5, rotor assembly 210 is generally formed with a rotor core or yoke 242 that is configured to carry a plurality of magnets 244. In one or more embodiments, rotor core 242 is spider shaped with fingers 248 extending radially from hub 246. Fingers 248 are spaced apart around the circumference of hub 246 to form magnet pockets 250 between adjacent fingers 248. In one or more embodiments, rotor assembly 210 further includes a rotor ring 252 that is radially outward from fingers 248. In one or more embodiments, rotor ring 252 and rotor core 242 may be separate components, as shown, for example, in FIGS. 1, 2A, and 2B, while in other embodiments rotor ring 252 and rotor core 242 may be formed integrally.

[0059] In one or more embodiments, rotor core 242 is formed from a non-conductive composite material. Similarly, in one or more embodiments, rotor ring 252 is formed from a non-conductive composite material.

[0060] 6 and 7, embodiments of rotor assembly 210 are illustrated and generally described as rotor assembly 310. Rotor assembly 310 generally includes a rotor core or yoke 342 configured to carry a plurality of magnets 344. In one or more embodiments, rotor core 342 is spider-shaped with fingers 348 extending radially from a hub 346. Fingers 348 are spaced apart around the circumference of hub 346 to define magnet pockets 350 between adjacent fingers 348. Rotor assembly further includes a rotor ring 352 configured radially outward from fingers 348. While not limited to a particular number of fingers 348 and pockets 350, in the illustrated embodiment, rotor core 342 has ten fingers 348 and ten magnet pockets 350.

[0061] In the illustrated embodiment of rotor assembly 310, fingers 348 are generally rectangular in shape such that magnet pockets 350 are generally wedge-shaped.

[0062] Thus, in the illustrated embodiment, the magnets 344 are generally wedge-shaped, with each magnet 344 having a radially outer edge 360 ​​that is longer than the radially inner edge 362, with the edges 360, 362 joined to one another by side edges 364. In one or more embodiments, a groove or slot 366 extends between the radially outer edge 360 ​​and the radially inner edge 362 along at least a portion of the length of at least one, and preferably each, side edge 364 of the magnets 344, as best seen in FIG. 8B. In one or more embodiments, each groove 366 extends completely between the radially outer edge 360 ​​and the radially inner edge 362, while in other embodiments, the groove 366 extends from the radially outer edge 360, which is spaced apart from the radially inner edge 362. In yet another embodiment, the groove 366 is spaced apart from the radially outer edge 360, which is spaced apart from the radially inner edge 362. Finally, in another embodiment, groove 366 is formed alongside edge 364 such that it is spaced from both radially outer edge 360 ​​and radially inner edge 362 .

[0063] Similarly, each finger 348 of the hub 346 has a side edge 368 that extends from a proximal end 369a located adjacent the hub 346 to a distal end 369b located at the periphery of the rotor core 342. In one or more embodiments, the side edge 368 of each finger may be generally smooth without any features formed therealong. In one or more other embodiments, each side edge 368 of the fingers 348 has a groove or slot 370 that extends between the proximal end 369a and the distal end 369b of the finger 348 along at least a portion of the length of the side edge 368.

[0064] In one embodiment, each groove 370 extends completely between the proximal end 369a and the distal end 369b of the finger 348, while in other embodiments, the groove 370 extends from the distal end 369b and is spaced from the proximal end 369a. In yet another embodiment, the groove 370 extends from the proximal end 369a and is spaced from the distal end 369b. Finally, in other embodiments, the groove 370 is formed alongside the edge 368 such that it is spaced from both the distal end 369b and the proximal end 369a of the finger 348.

[0065] In one or more embodiments, the rotor ring 352 is a preformed ring disposed about the rotor core 342. In some embodiments, the rotor ring 352 is a continuous solid ring. In this regard, the rotor ring 352 may be formed of a composite material, such as a fiber material. The rotor ring 352 has a radially inner edge 376 and a radially outer edge 378, where the radially inner edge 376 abuts the fingers 348 when disposed about the rotor core 342. In one or more embodiments, the radially inner edge 376 of the preformed solid rotor ring 352 is formed. Of course, the carbon fiber material and the glass fiber material may each be formed of a fiber-bearing substrate.

[0066] 8, in one or more embodiments, the rotor core or yoke 342 may be formed from multiple plies 380 of fibrous material arranged in a stack 382 or "book" as shown. Each fibrous ply 380 may be material with a set of primary fibers. The individual plies 380 are formed into a stack 382.

[0067] Thus, an electric drive assembly has been described. In one or more embodiments, the electric drive assembly includes a first axial flux motor and a main drive shaft having a first end and a second end, the main drive shaft disposed along a first axis and coupled to the first axial flux motor, the electric drive assembly includes a second axial flux motor disposed adjacent to the first axial flux motor and an assist drive shaft having a first end and a second end, the assist drive shaft being hollow, the assist drive shaft having an outer drive shaft surface and an inner bore extending therethrough between the first end and the second end of the assist drive shaft, the assist drive shaft being coupled to the second axial flux motor, the main drive shaft extending through the assist drive shaft coaxially with the assist drive shaft, the electric drive assembly includes a main gear fixed to the main drive shaft and a gear mounted along the assist drive shaft. the electric drive assembly includes an assist gear mounted on the intermediate drive shaft and rotatable independently of the assist drive shaft, and an intermediate drive shaft extending along a second axis, the intermediate drive shaft parallel to but spaced from the first axis, the electric drive assembly including a first intermediate gear mounted on the intermediate drive shaft and in continuous mesh with the assist gear, a second intermediate gear mounted on the intermediate drive shaft and in continuous mesh with the main gear, a third intermediate gear mounted on the intermediate drive shaft, an output drive shaft disposed along the first axis but spaced from the first and second drive shafts, an output gear fixed to the output drive shaft and in continuous mesh with the third intermediate gear, and a shift mechanism mounted along the assist drive shaft and axially movable along the assist drive shaft between the main gear and the assist gear. In one or more embodiments, the electric drive assembly may include a first axial flux motor and a main drive shaft having a first end and a second end, the main drive shaft disposed along a first axis and coupled to the first axial flux motor, the electric drive assembly comprising:The electric drive assembly may include a second axial flux motor disposed adjacent to the first axial flux motor and an assist drive shaft having a first end and a second end, the assist drive shaft having an inner bore extending therethrough between the first and second ends of the assist drive shaft and an outer drive shaft surface having a guide mechanism 150 formed on the outer drive shaft surface, the assist drive shaft being coupled to the second axial flux motor, the main drive shaft extending through the assist drive shaft so as to be coaxial with the assist drive shaft, the electric drive assembly may include a main gear secured to the main drive shaft, the main gear having a first face, an opposing second face and an outer circumferential surface, the radially extending teeth being formed along the outer circumferential surface, the first axial engagement mechanism being formed on the first face adjacent the outer circumferential surface of the main gear, the electric drive assembly may include an assist gear mounted along the assist drive shaft and rotatable independently of the assist drive shaft, the assist gear having a first face, an opposing second face and an outer circumferential surface having a radially extending tooth formed thereon, The assist gear may have a first face, an opposing second face and an outer circumferential surface with radially extending teeth formed along the outer circumferential surface, a second axial engagement mechanism formed on the second face adjacent the outer circumferential surface of the assist gear, the electric drive assembly may include an intermediate drive shaft extending along a second axis, the intermediate drive shaft being parallel to but spaced from the first axis, the electric drive assembly including a first intermediate gear attached to the intermediate drive shaft and in continuous mesh with the assist gear, and a second intermediate gear attached to the intermediate drive shaft. a second intermediate gear attached to the intermediate drive shaft and in continuous meshing with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft disposed along the first axis but spaced from the first and second drive shafts; an output gear fixed to the output drive shaft and in continuous meshing with the third intermediate gear; and a dog ring coupled to the assist drive shaft and axially movable along the assist drive shaft between the main gear and the assist gear, the dog ring beingThe electric drive assembly may have a central hole with a radially extending notch that engages with a guide mechanism of the assist drive shaft, and the electric drive assembly may include an engagement mechanism configured to couple with one of the first axial engagement mechanism or the second axial engagement mechanism. In one or more other embodiments, the electric drive assembly can include a first axial flux motor with a single non-metallic rotor and a main drive shaft with a first end and a second end, the main drive shaft disposed along a first axis and coupled to the first axial flux motor, the electric drive assembly can include a second axial flux motor disposed adjacent to the first axial flux motor, the second axial flux motor having a single non-metallic rotor, the electric drive assembly can include an assist drive shaft with a first end and a second end, the assist drive shaft having an inner bore extending therethrough between the first and second ends of the assist drive shaft and an outer drive shaft surface, the assist drive shaft is coupled to the second axial flux motor, the main drive shaft extends through the assist drive shaft coaxially with the assist drive shaft, and the electric drive assembly can include a main drive shaft secured to the main drive shaft. the main gear may include a main gear having a first face, an opposing second face and an outer circumferential surface, with radially extending teeth formed along the outer circumferential surface, and a first axial engagement mechanism formed on the first face adjacent the outer circumferential surface of the main gear; the electric drive assembly may include an assist gear mounted along the assist drive shaft and rotatable independently of the assist drive shaft, the assist gear having a first face, an opposing second face and an outer circumferential surface, with radially extending teeth formed along the outer circumferential surface, and a second axial engagement mechanism formed on the second face adjacent the outer circumferential surface of the assist gear; the electric drive assembly may include an intermediate drive shaft extending along a second axis, the intermediate drive shaft being parallel to but spaced from the first axis; the electric drive assembly may include a first intermediate gear mounted on the intermediate drive shaft and in continuous mesh with the assist gear, and an intermediate gear mounted on the intermediate drive shaft;a second intermediate gear and in continuous meshing with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft disposed along the first axis but spaced from the first and second drive shafts; an output gear fixed to the output drive shaft and in continuous meshing with the third intermediate gear; a dog ring coupled to the assist drive shaft and axially movable along the assist drive shaft between the main gear and the assist gear; and coupled to one of the first axial engagement mechanism or the second axial engagement mechanism. and a shift mechanism provided to move the dog ring axially along the outer surface of the assist drive shaft, the shift mechanism including an electric actuator, and the electric drive assembly may include a first speed sensor provided adjacent one of the drive shafts to monitor the rotational speed of the drive shaft, a single inverter electrically coupled to each of the first and second axial flux motors and the electric actuator, and a single controller controlling each of the first and second axial flux motors and the electric actuator. In one or more other embodiments, the electric drive assembly is a two-speed electric drive assembly, the two-speed electric drive assembly including a main drive shaft along which a main gear is disposed, the two-speed electric drive assembly including a first axial flux motor coupled to and arranged to rotate the main drive shaft, and an assist drive shaft along which an assist gear is disposed, the two-speed electric drive assembly including a second axial flux motor coupled to and arranged to rotate the assist drive shaft, and an intermediate drive shaft, first, second and third intermediate gears are each disposed along the intermediate drive shaft, the third intermediate gear is fixed to the intermediate drive shaft, the two-speed electric drive assembly includes an output drive shaft having an output gear attached thereto, the main gear is in continuous mesh with the second intermediate gear, the assist gear is in continuous mesh with the first intermediate gear, and the output gear isThe third intermediate gear is continuously meshed with the main gear, the assist gear, the first intermediate gear or the second intermediate gear, and one of the main gear, the assist gear, the first intermediate gear or the second intermediate gear is a freewheel gear, and the freewheel gear is arranged to be rotatable independently of the drive shaft on which the freewheel gear is fitted.

[0068] For any of the above embodiments, the rotor assembly may include any one of the following features, either alone or in combination with each other. The first axial flux motor is adjacent to the second axial flux motor. The main drive shaft passes through and is coaxial with the assist drive shaft. A first axial flux motor coupled to the main drive shaft. A second axial flux motor coupled to the assist drive shaft. A shift mechanism disposed adjacent the freewheel gear and axially movable to couple and disengage the freewheel gear from the drive shaft on which it is fitted. The shift mechanism includes a hub attached to the drive shaft and a shift sleeve that slidingly engages the fixed hub. The output drive shaft is collinear with the main drive shaft and the hollow assist drive shaft. The assist drive shaft is hollow, and the main drive shaft coaxially passes through the assist drive shaft. The intermediate drive shaft is parallel to the main drive shaft and the assist drive shaft. The main drive shaft extends along a first axis and the intermediate drive shaft extends along a second axis spaced from the main first axis. The assist gear is a freewheel gear. The main gear is a freewheel gear. The first intermediate gear is a freewheel gear. The second intermediate gear is a freewheel gear. One or more bearings provided between the assist gear and the assist drive shaft so that the assist gear can rotate about the first axis independently of the assist drive shaft. The assist gear is a freewheel gear, and the electric drive assembly further includes a plurality of cooperating elements provided on the assist gear and a plurality of cooperating elements provided on the shift mechanism to engage with the plurality of cooperating elements provided on the assist gear. A first speed sensor disposed adjacent the intermediate drive shaft for monitoring the rotational speed of the intermediate drive shaft. A first speed sensor disposed adjacent one of the drive shafts for monitoring the rotational speed of the drive shaft. A first speed sensor disposed adjacent the assist drive shaft for monitoring the rotational speed of the assist drive shaft. The first velocity sensor is electrically coupled to the actuator. A second speed sensor located adjacent to the dog ring. A first speed sensor disposed adjacent the assist drive shaft for monitoring the rotational speed of the assist drive shaft and a second speed sensor disposed adjacent one of the main drive shaft or the first main gear. A single inverter electrically coupled to each of the first and second axial flux motors and the electric actuator. A single controller controls each of the first and second axial flux motors and the electric actuator. The first axial flux motor has only a single rotor. The second axial flux motor has only a single rotor. The first and second axial flux motors each include only a single rotor. The first axial flux motor includes a non-metallic rotor. The first and second flux motors each include a non-metallic rotor. The first and second flux motors each include a single rotor disposed between two stators. The output drive shaft is parallel to the intermediate drive shaft. The main drive shaft, hollow assist drive shaft, intermediate drive shaft and output drive shaft are all spatially fixed relative to one another within the gearbox housing. A gearbox housing containing the gears and drive shaft. The axial flux motor is located outside the gearbox housing. Two or more axial flux motors coupled to a main drive shaft. Two or more axial flux motors coupled to an assist drive shaft. a first support plate and a second support plate disposed within the gearbox housing, an assist drive shaft supported by the gearbox housing and the first support plate, an output drive shaft supported by the gearbox housing and the second support plate, and a main drive shaft extending from the assist drive shaft and supported by the second support plate. The intermediate drive shaft is supported by first and second support plates. The intermediate drive shaft is supported by the gearbox housing. The main gear has a first radius R1, the assist gear has a second radius R2, the first intermediate gear has a third radius R3, the second intermediate gear has a fourth radius R3, the third intermediate gear has a fifth radius R5, and the output gear has a sixth radius R6. R3 is greater than R4, R4 is greater than R5, R6 is greater than R1, R1 is greater than R2.

[0069] While various embodiments have been shown and described, it is to be understood that the invention is not limited to such embodiments, but includes all modifications and variations apparent to those skilled in the art. Therefore, it is not intended that the invention be limited to the particular forms disclosed, but rather, the invention is intended to include all modifications, equivalents, and variations falling within the spirit and scope of the invention as defined by the appended claims.

Claims

1. 1. An electric drive assembly comprising: a main drive shaft, a main gear provided along the main drive shaft; a first axial flux motor coupled to the main drive shaft and configured to rotate the main drive shaft; An assist drive shaft is included, and an assist gear is provided along the assist drive shaft, a second axial flux motor coupled to the assist drive shaft and positioned to rotate the assist drive shaft; an intermediate drive shaft, first, second and third intermediate gears respectively provided along the intermediate drive shaft, the third intermediate gear being fixed to the intermediate drive shaft; an output drive shaft, the output gear being attached to the output drive shaft; the main gear is continuously meshed with the second intermediate gear; the assist gear is continuously meshed with the first intermediate gear, the output gear is continuously meshed with the third intermediate gear; an electric drive assembly, wherein one of the main gear, the assist gear, the first intermediate gear, or the second intermediate gear is a freewheel gear, the freewheel gear being rotatable independently of the drive shaft on which the freewheel gear is fitted;

2. 2. The electric drive assembly of claim 1, further comprising a shift mechanism disposed adjacent said freewheel gear and axially movable to couple and discouple said freewheel gear to and from said drive shaft on which said freewheel gear is fitted.

3. 2. The electric drive assembly of claim 1, wherein the assist drive shaft is hollow and the main drive shaft coaxially extends through the assist drive shaft.

4. 4. The electric drive assembly of claim 3, wherein said main drive shaft extends along a first axis and said intermediate drive shaft extends along a second axis spaced from said main first axis.

5. 5. The electric drive assembly of claim 4, wherein said assist gear is said freewheel gear.

6. 3. The electric drive assembly of claim 2, further comprising one or more bearings disposed between the assist gear and the assist drive shaft to enable the assist gear to rotate about the first axis independently of the assist drive shaft.

7. 3. The electric drive assembly of claim 2, wherein the assist gear is the freewheel gear, and the electric drive assembly further includes a plurality of cooperating elements provided on the assist gear and a plurality of cooperating elements provided on the shift mechanism to engage the plurality of cooperating elements provided on the assist gear.

8. 1. A two-speed electric drive assembly comprising: a first axial flux motor; a main drive shaft having a first end and a second end, the main drive shaft disposed along the first axis and coupled to the first axial flux motor; a second axial flux motor disposed adjacent to the first axial flux motor; an assist drive shaft having a first end and a second end, the assist drive shaft being hollow, the assist drive shaft having an outer drive shaft surface and an inner bore extending therethrough between the first end and the second end of the assist drive shaft, the assist drive shaft being coupled to the second axial flux motor, the main drive shaft extending through the assist drive shaft so as to be coaxial with the assist drive shaft; a main gear fixed to the main drive shaft; an assist gear attached along the assist drive shaft and rotatable independently of the assist drive shaft; an intermediate drive shaft extending along a second axis, the intermediate drive shaft being parallel to but spaced apart from the first axis; a first intermediate gear attached to the intermediate drive shaft and permanently meshed with the assist gear; a second intermediate gear attached to the intermediate drive shaft and permanently meshed with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft disposed along the first axis but spaced apart from the first and second drive shafts; an output gear fixed to said output drive shaft and permanently meshed with said third intermediate gear; a two-speed electric drive assembly including a shift mechanism mounted along the assist drive shaft and axially movable along the assist drive shaft between the main gear and the assist gear;

9. 9. The two-speed electric drive assembly of claim 8, wherein said main gear has a first radius R1, said assist gear has a second radius R2, said first intermediate gear has a third radius R3, said second intermediate gear has a fourth radius R3, said third intermediate gear has a fifth radius R5, and said output gear has a sixth radius R6, wherein R3 is greater than R4, which is greater than R5, which is greater than R1, which is greater than R2.

10. 9. The two-speed electric drive assembly of claim 8, further comprising a gearbox housing having a first support plate and a second support plate disposed within the gearbox housing, the assist drive shaft being supported by the gearbox housing and the first support plate, the output drive shaft being supported by the gearbox housing and the second support plate, and the main drive shaft extending from the assist drive shaft and supported by the second support plate.

11. The two-speed electric drive assembly of claim 10 , wherein said intermediate drive shaft is supported by said gearbox housing.

12. 9. The two-speed electric drive assembly of claim 8, further including an electric actuator provided to operate said shifting mechanism, and a single inverter electrically coupled to each of said first and second axial flux motors and said electric actuator.

13. The two-speed electric drive assembly of claim 12 further comprising a single controller controlling said single inverter.

14. 14. The two-speed electric drive assembly of claim 13, further comprising: a first speed sensor mounted adjacent the assist drive shaft to monitor the rotational speed of the assist drive shaft; and a second speed sensor mounted adjacent one of the main drive shaft, the first main gear, the intermediate drive shaft, or the intermediate gear to monitor the rotational speed of the assist gear.

15. 1. An electric drive assembly comprising: a first axial flux motor; a main drive shaft having a first end and a second end, the main drive shaft disposed along the first axis and coupled to the first axial flux motor; a second axial flux motor; an assist drive shaft having a first end and a second end, the assist drive shaft disposed along the first axis and coupled to the second axial flux motor; a main gear provided around the main drive shaft; an assist gear provided around the assist drive shaft, one of the main gear and the assist gear being a freewheel gear, the freewheel gear being rotatable independently of the drive shaft on which the freewheel gear is fitted; an intermediate drive shaft extending along a second axis, the second axis being parallel to but spaced apart from the first axis; a first intermediate gear disposed around the intermediate drive shaft and permanently meshed with the assist gear; a second intermediate gear mounted about the intermediate drive shaft and permanently meshed with the main gear; a third intermediate gear attached to the intermediate drive shaft; an output drive shaft spaced apart from the main drive shaft and the assist drive shaft; an output gear fixed to said output drive shaft and permanently meshed with said third intermediate gear; 1. An electric drive assembly comprising: a shift mechanism mounted adjacent to the freewheel gear, the shift mechanism being axially movable along the first axis from a first position in which the shift mechanism engages the freewheel gear to couple the freewheel gear to the drive shaft to which the freewheel gear is attached, to a second position in which the shift mechanism is disengaged from the freewheel gear.

16. 16. The two-speed electric drive assembly of claim 15, further comprising an electric actuator provided to operate said shifting mechanism, a single inverter electrically coupled to each of said first and second axial flux motors and said electric actuator, and a controller controlling said single inverter.

17. 17. The two-speed electric drive assembly of claim 16, further comprising: a first speed sensor mounted adjacent the assist drive shaft to monitor the rotational speed of the assist drive shaft; and a second speed sensor mounted adjacent one of the main drive shaft, the first main gear, the intermediate drive shaft, or the intermediate gear to monitor the rotational speed of the assist gear.

18. 17. The two-speed electric drive assembly of claim 16, wherein said first axial flux motor includes only a single rotor.

19. 17. The two-speed electric drive assembly of claim 16, wherein said first and second flux motors each include only a single rotor.

20. 20. The two-speed electric drive assembly of claim 19, wherein said first and said second flux motors each include a non-metallic rotor.

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